How did climate science become so politicized? Just a few years ago, Senators John McCain and Lindsay Graham were among conservatives who accepted the basic physics of heat trapping gases and the need to decouple carbon pollution from economic growth. Today, many candidates claim the science is unsettled and scientists are the targets of smear campaigns.Time: 4:30 p.m. check-in, 5-6 p.m. program

NASA climatologist Hansen has grown increasingly concerned about the risks of climatic tipping points, which could bring catastrophic consequences. His recent research also is identifying human fingerprints on specific instances of extreme weather, putting him out in front of many of his peers. There is a yawning gap between what scientists understand and what the public knows. Hansen is the recipient of the 2012 Stephen Schneider Award for Climate Science Communication, a $10,000 award in memory of the late great Stanford climate scientist and former member of the Climate One Advisory Council. At the end of the program, climate scientist Ben Santer will present Hansen with the award for his achievements.Time: 6:30-7:30 p.m. program